Name: in vitro and in vivo models to study corneal endothelial-mesenchymal transition
Uploaded: 2016-08-20T14:00:00
Description: Watch this Scientific Journal Video about In Vitro and In Vivo Models to Study Corneal Endothelial-mesenchymal Transition at JoVE.com

We thank the staff of the Second Core Lab, Department of Medical Research, National Taiwan University Hospital for their technical support.

All the procedures followed in this study accorded with the Association for Research in Vision and Ophthalmology Statement for Use of Animals in Ophthalmic and Vision Research and were approved by the Institutional Animal Care and Use Committee of National Taiwan University Hospital.
1. Isolation, Primary Culture Preparation, and Immunostaining of Bovine CECs
<ol>
	<li>Acquire fresh bovine eyes from a local abattoir.</li>
	<li>Disinfect the eyes in a 10% w/v povidone-iodine solution for 3 min. Wash them with pho...

<ol>
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T., Chen, H. C., Chen, S. Y., Tseng, S. C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nuclear+p120+catenin+unlocks+mitotic+block+of+contact-inhibited+human+corneal+endothelial+monolayers+without+disrupting+adherent+junctions.">Nuclear p120 catenin unlocks mitotic block of contact-inhibited human corneal endothelial monolayers without disrupting adherent junctions.</a> J Cell Sci. 125 (15), 3636-3648 (2012).</li><li>Ho, W. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+of+Matrix+Metalloproteinase+Activity+Reverses+Corneal+Endothelial-Mesenchymal+Transition.">Inhibition of Matrix Metalloproteinase Activity Reverses Corneal Endothelial-Mesenchymal Transition.</a> Am J Pathol. 185 (8), 2158-2167 (2015).</li><li>Kay, E. D., Cheung, C. C., Jester, J. V., Nimni, M. E., Smith, R. 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CECs are known for their propensity to undergo EnMT during cell proliferation. To develop strategies for suppressing the EnMT process for therapeutic purposes, a thorough understanding of the EnMT mechanism is necessary. We described 2 models to investigate EnMT, namely the bovine CEC in vitro culture model and rat corneal endothelium cryoinjury model. Our results demonstrated the EnMT process in both models. Furthermore, the EnMT-suppressing effect of marimastat was reproduced in both models, suggesting that th...

Corneal endothelial cells (CECs) play a vital role in maintaining corneal clarity and thus visual acuity by regulating the hydration status of the corneal stroma through active pumping1. Because of the limited proliferative potential of human CECs, the cell number decreases with age, and the repair of corneal endothelial wounds following injury is usually achieved through cell enlargement and migration, rather than cell mitosis2. When the CEC count decreases below a threshold of approximately 500 cells/mm2, the dehydration status of the corneal stroma cannot be maintained, leading to bullous keratopathy and vision impairment3,4.
The limited proliferative potential of human CECs has been attributed to several factors, including reduced expression of the epidermal growth factor and its receptor in aging cells5, antiproliferative TGF&#946;2 in the aqueous humor6, and contact inhibition2,7. Although some growth factors, such as basic fibroblast growth factor (bFGF), can increase proliferation in a cultured human corneal endothelium, the culture efficiency remains limited8,9. Furthermore, CECs may undergo a phenotypic change during ex vivo expansion, resembling epithelial-mesenchymal transition (EMT)10-13. Endothelial-mesenchymal transition (EnMT) is characterized by cell junction destabilization, apical-basal polarity loss, cytoskeletal rearrangement, alpha smooth muscle actin expression, and type I collagen secretion14. All of these characteristics may abrogate the normal function of CECs, hampering the use of ex vivo cultured CECs in tissue engineering. Moreover, EnMT has been associated with the pathogenesis of several corneal endothelial diseases, including Fuchs endothelial corneal dystrophy and retrocorneal membrane formation15,16. Therefore, understanding the mechanism of EnMT may aid in manipulating the EnMT process and facilitate the regeneration of CECs to enable competent function. 
In this study, we described a method for isolating bovine CECs from the corneal button. In the primary culture in vitro, the EnMT process, including a phenotypic change, the nuclear translocation of &#946;-catenin, and EMT regulators snail and slug, was observed. We further described a method for demonstrating EnMT in vivo by using a rat corneal endothelium cryoinjury model. Using these 2 models, we demonstrated that marimastat, a broad-spectrum matrix metalloproteinase (MMP) inhibitor, can suppress the EnMT process. The described protocols facilitate the detailed analysis of the EnMT mechanism and the development of strategies for manipulating the EnMT process for further clinical application.

<table border="0" cellpadding="0" cellspacing="0" width="1447">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:695px;">trypsin</td>
			<td style="width:269px;">ThermoFisher Scientific</td>
			<td style="width:143px;">12604-013</td>
			<td style="width:340px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dulbecco&#8217;s modified Eagle medium and Ham&#39;s F12 medium</td>
			<td>ThermoFisher Scientific</td>
			<td>11330</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">fetal bovine serum</td>
			<td>ThermoFisher Scientific</td>
			<td>26140-079</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">dimethyl sulfoxide</td>
			<td>Sigma</td>
			<td>D2650</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">human epidermal growth factor</td>
			<td>ThermoFisher Scientific</td>
			<td>PHG0311</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">insulin, transferrin, selenium&#160;</td>
			<td>ThermoFisher Scientific</td>
			<td>41400-045</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">cholera toxin</td>
			<td>Sigma</td>
			<td>C8052-1MG</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">gentamicin</td>
			<td>ThermoFisher Scientific</td>
			<td>15750-060</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">amphotericin B</td>
			<td>ThermoFisher Scientific</td>
			<td>15290-026</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">paraformaldehyde</td>
			<td>Electron Microscopy Sciences</td>
			<td>111219</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Triton X-100</td>
			<td>Sigma</td>
			<td>T8787&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">bovine serum albumin</td>
			<td>Sigma</td>
			<td>A7906</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">marimastat</td>
			<td>Sigma</td>
			<td>M2699-25MG</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">anti-active beta-catenin antibody</td>
			<td>Millpore</td>
			<td>05-665</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">anti-snail antibody</td>
			<td>Santa cruz</td>
			<td>sc28199</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">anti-slug antibody</td>
			<td>Santa cruz</td>
			<td>sc15391</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">goat anti-mouse IgG (H+L) secondary antibody</td>
			<td>ThermoFisher Scientific</td>
			<td>A-11001</td>
			<td>for staining of ABC of bovine CECs</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">goat anti-mouse IgG (H+L) secondary antibody</td>
			<td>ThermoFisher Scientific</td>
			<td>A-11003</td>
			<td>for staining of ABC of rat corneal endothelium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">goat anti-rabbit IgG (H+L) secondary antibody</td>
			<td>ThermoFisher Scientific</td>
			<td>A-11008</td>
			<td>for staining of snail and slug of bovine CECs</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">antibody diluent</td>
			<td>Genemed Biotechnologies</td>
			<td>10-0001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">4&#39;,6-diamidino-2-phenylindole</td>
			<td>ThermoFisher Scientific</td>
			<td>D1306</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">mounting medium</td>
			<td>Vector Laboratories</td>
			<td>H-1000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">laser scanning confocal microscope</td>
			<td>ZEISS</td>
			<td>LSM510</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">xylazine&#160;</td>
			<td>Bayer</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">tiletamine plus zolazepam</td>
			<td>Virbac</td>
			<td>N/A</td>
			<td>veterinary drug</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">proparacaine hydrochloride ophthalmic solution</td>
			<td>Alcon</td>
			<td>N/A</td>
			<td>veterinary drug</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">0.1% atropine</td>
			<td>Wu-Fu Laboratories Co., Ltd</td>
			<td>N/A</td>
			<td>clinical drug&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">0.3% gentamicin sulfate</td>
			<td>Sinphar Group</td>
			<td>N/A</td>
			<td>clinical drug&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">basic fibroblast growth factor</td>
			<td>ThermoFisher Scientific</td>
			<td>PHG0024</td>
			<td>clinical drug&#160;</td>
		</tr>
	</tbody>
</table>

in vitro and in vivo models to study corneal endothelial-mesenchymal transition

Corneal endothelial cells (CECs) play a crucial role in maintaining corneal clarity through active pumping. A reduced CEC count may lead to corneal edema and diminished visual acuity. However, human CECs are prone to compromised proliferative potential. Furthermore, stimulation of cell growth is often complicated by gradual endothelial-mesenchymal transition (EnMT). Therefore, understanding the mechanism of EnMT is necessary for facilitating the regeneration of CECs with competent function. In this study, we prepared a primary culture of bovine CECs by peeling the CECs with Descemet's membrane from the corneal button and demonstrated that bovine CECs exhibited the EnMT process, including phenotypic change, nuclear translocation of &#946;-catenin, and EMT regulators snail and slug, in the in vitro culture. Furthermore, we used a rat corneal endothelium cryoinjury model to demonstrate the EnMT process in vivo. Collectively, the in vitro primary culture of bovine CECs and in vivo rat corneal endothelium cryoinjury models offers useful platforms for investigating the mechanism of EnMT.

After the isolation of bovine CECs, the cells were cultured in vitro. Figure 1 presents the phase contrast images of the bovine CECs. The hexagonal shape of the cells at confluence indicated that the cells were not contaminated by corneal stromal fibroblast during cell isolation. Figure 2 depicts the immunostaining that was performed using antibodies against ABC, snail, and slug at an indicated time point. Apart from phenotypic changes in the <em...

Watch this Scientific Journal Video about In Vitro and In Vivo Models to Study Corneal Endothelial-mesenchymal Transition at JoVE.com

In Vitro and In Vivo Models to Study Corneal Endothelial-mesenchymal Transition

A primary culture of bovine corneal endothelial cells was used to investigate the mechanism of corneal endothelial-mesenchymal transition. Furthermore, a rat corneal endothelium cryoinjury model was used to demonstrate corneal endothelial-mesenchymal transition in vivo.

In Vitro and In Vivo Models to Study Corneal Endothelial-mesenchymal Transition

Corneal endothelial cells (CECs) play a crucial role in maintaining corneal clarity through active pumping. A reduced CEC count may lead to corneal edema ...

The overall goal of this procedure is to investigate the mechanism of Corneal Endothelial-mesenchymal Transition In Vitro and In Vivo. This method can help answer questions about Corneal Endothelial-mesenchymal Transition in the field of Corneal Endothelial regeneration. The advantage of this technique is that it can be applied to both In Vitro and the In Vivo models.And is easy to manipulate. The implications of this technique is tend towards therapy of disease related to Corneal Endothelial-mesenchymal Transition. Such as formation, because the models can be used to select to us that inhibits the process of Corneal Endothelial-mesenchymal Transition.The the procedure will be miss Jung-Shen Chang, a technician from a laboratory. To begin this procedure, disinfect fresh bovine eyes in a 10%weight per volume Povidone-iodine solution for three minutes. Then, wash them with PBS.Harvest the corneal button with a scalpel and scissors and wash it with PBS Under a dissecting microscope, peel the Descemet's Membrane with forceps. After that, incubate the Descemet's Membrane in one milliliter of Trypsin at 37 degrees Celsius for 30 minutes. Next, collect the bovine CECs by centrifugation at 112 times g for five minutes.After centrifugation, re-suspend the cells in one milliliter of SHEM. Seed the cells in a six centimeter dish and culture them in SHEM. Subsequently, incubate the cells at 37 degrees Celsius in 5%CO2 and change the culture medium every three days.When the cells reach confluence, wash them in PBS. Then, incubate them in one millimeter of Trypsin at 37 degrees Celsius for five minutes. Collect them by centrifugation at 112 times g for five minutes.After five minutes, re-suspend the cell pellet in one millimeter of SHEM. Next, count the cells in a Hemacytometer. Following that, seed the cells on cover slides in a 24-well plate and culture the cells in SHEM.For investigating the ENMT-suppressing effect of Maramastat, incubate the cells in SHEM with 10 micromolar Maramastat in the culture medium and change the culture medium every three days. Then, fix the cells at an indicated time point with 250 microliters of 4%Paraformaldehyde for 30 minutes at room temperature. Afterward, permeablize them with 250 microliters of 0.5%Triton X-100 for five minutes.And block them with 10%BSA for 30 minutes. Subsequently, incubate the cells with primary antibodies against ABC, snail, and slug overnight at four degrees Celsius. The next day, wash the cells twice with PBS for 15 minutes each time.And incubate them with the Alexa Fluor conjugated secondary antibody at room temperature for one hour. After that, counterstain the cell nucleus by covering the cells with DAPI at two micrograms per milliliter. Wash the cells twice with PBS for 15 minutes each time.And mount them with anti-fading mounting solution before obtaining the immunoflourescent images. After anesthetizing a 12-week old male SD rat, gently pinch the skin of the animal to confirm proper anesthesia in the absence of skin twitching. Then, apply a drop of 0.5%Proparacaine Hydrochloride to the rat's right eye to minimize pain and the blink reflex.Subsequently, apply Tetracycline ointment to the left eye to prevent corneal dryness. Next, cool a stainless steel probe in liquid Nitrogen. Apply the stainless steel probe to the central cornea of the right eye for 30 seconds.Frequently instill PBS to the right eye during the procedure to prevent corneal dryness and apply 0.1%Atropine and 0.3%Gentamicin Sulfate immediately after cryoinjury once daily to relieve ocular pain resulting from Ciliary spasm and to prevent infection. After the procedure, keep the rat warm using a heat lamp and observe its recovery until it regains motor control. Apply Tetracycline ointment to the right eye to prevent corneal dryness during the recovery period and repeat the corneal cryoinjury procedure for three consecutive days.For delivering Maramastat or basic FGF into the interior chamber of the rat eyes, apply a drop of 0.5%Proparacaine Hydrochloride to the right eye of the anesthetized rat to minimize pain and the blink reflex. Next, irrigate the ocular surface with sterile PBS. Under an operating microscope, perform anterior chamber paracentesis by inserting a 30 gauge needle attached to a one millimeter syringe at the paralimbal clear cornea in a plain, above, and parallel to the iris Then, turn the needle bevel up and slightly depress the corneal wound to drain some aqueous humor and reduce the interocular pressure.Inject 0.02 milliliters of the drug intracamerally and gently compress the needle tract with a cotton tip during the needle withdraw. This figure presents the phase contrast images of the bovine CECs and cultures. The hexagonal shape of the cells at confluence indicates that the cells are not contaminated by corneal stromal fibroblasts during cell isolation.During the In Vitro culture of bovine CECs, the nuclear translocation of ABC, snail, and slug was detected through day 14. This figure illustrates the effect of Maramastat, a broad spectrum MMP inhibitor on the ENMT process of the In Vitro cultured bovine CECs. Here, are the external eye photographs of rats after cryoinjury, followed by intracameral injection.The photographs show reduced corneal edema after basic FGF injection. Whereas Maramastat further reduced corneal edema compared with basic FGF alone. And this figure shows immunostaining of the rat corneal button using antibody against ABC after cryoinjury followed by intracameral injection.The nuclear translocation of ABC is observed in the PBS group and is significantly increased in the basic FGF group, indicating activation of Wnt Beta-catenin signalling and the ENMT process. After intracameral injection, a basic FGF followed by Maramastat, the nuclear staining of ABC is diminished, suggesting the ENMT-inhibiting effect of Maramastat. After its development, this technique pave the way for researchers in the field of Corneal Endothelial-mesenchymal Transition, In Vitro and the In Vivo.After watching this video, you should have a good understanding of how to isolate bovine corneal endothelial cells and to perform corneal cryoinjury as well as intracameral injection

in-vitro-vivo-models-to-study-corneal-endothelial-mesenchymal

Research

JoVE Journal

Developmental Biology

Characterization of Thymic Settling Progenitors in the Mouse Embryo Using In Vivo and In Vitro Assays

Characterizing thymic settling progenitors is important to understand the pre-thymic stages of T cell development, essential to devise strategies for T cell replacement in lymphopenic patients. We studied thymic settling progenitors from murine embryonic day 13 and 18 thymi by two complementary in vitro and in vivo techniques, both based on the &#8220;hanging drop&#8221; method. This method allowed colonizing irradiated fetal thymic lobes with E13 and/or E18 thymic progenitors distinguished by CD45 allotypic markers and thus following their progeny. Colonization with mixed populations allows analyzing cell autonomous differences in biologic properties of the progenitors while colonization with either population removes possible competitive selective pressures. The colonized thymic lobes can also be grafted in immunodeficient male recipient mice allowing the analysis of the mature T cell progeny in vivo, such as population dynamics of the peripheral immune system and colonization of different tissues and organs. Fetal thymic organ cultures revealed that E13 progenitors developed rapidly into all mature CD3+ cells and gave rise to the canonical &#947;&#948; T cell subset, known as dendritic epithelial T cells. In comparison, E18 progenitors have a delayed differentiation and were unable to generate dendritic epithelial T cells. The monitoring of peripheral blood of thymus-grafted CD3-/- mice further showed that E18 thymic settling progenitors generate, with time, larger numbers of mature T cells than their E13 counterparts, a feature that could not be appreciated in the short term fetal thymic organ cultures.

Characterization of Thymic Settling Progenitors in the Mouse Embryo Using In Vivo and In Vitro Assays

This article describes in vivo and in vitro methodology to characterize the thymic settling progenitors by the analysis of the kinetics of generation, phenotype and numbers of their T cell progeny.

Characterizing thymic settling progenitors is important to understand the pre-thymic stages of T cell development, essential to devise strategies for T ...

Stem cell-like Xenopus Embryonic Explants to Study Early Neural Developmental Features In Vitro and In Vivo

Understanding the genetic programs underlying neural development is an important goal of developmental and stem cell biology. In the amphibian blastula, cells from the roof of the blastocoel are pluripotent. These cells can be isolated, and programmed to generate various tissues through manipulation of genes expression or induction by morphogens. In this manuscript protocols are described for the use of Xenopus laevis blastocoel roof explants as an assay system to investigate key in vivo and in vitro features of early neural development. These protocols allow the investigation of fate acquisition, cell migration behaviors, and cell autonomous and non-autonomous properties. The blastocoel roof explants can be cultured in a serum-free defined medium and grafted into host embryos. This transplantation into an embryo allows the investigation of the long-term lineage commitment, the inductive properties, and the behavior of transplanted cells in vivo. These assays can be exploited to investigate molecular mechanisms, cellular processes and gene regulatory networks underlying neural development. In the context of regenerative medicine, these assays provide a means to generate neural-derived cell types in vitro that could be used in drug screening.

Stem cell-like Xenopus Embryonic Explants to Study Early Neural Developmental Features In Vitro and In Vivo

In Xenopus embryos, cells from the roof of the blastocoel are pluripotent and can be programmed to generate various tissues. Here, we describe protocols to use amphibian blastocoel roof explants as an assay system to investigate key in vivo and in vitro features of early neural development.

Understanding the genetic programs underlying neural development is an important goal of developmental and stem cell biology. In the amphibian blastula, ...

Development of an In Vitro Assay to Evaluate Contractile Function of Mesenchymal Cells that Underwent Epithelial-Mesenchymal Transition

Fibrosis is often involved in the pathogenesis of various chronic progressive diseases such as interstitial pulmonary disease. Pathological hallmark is the formation of fibroblastic foci, which is associated with the disease severity. Mesenchymal cells consisting of the fibroblastic foci are proposed to be derived from several cell sources, including originally resident intrapulmonary fibroblasts and circulating fibrocytes from bone marrow. Recently, mesenchymal cells that underwent epithelial-mesenchymal transition (EMT) have been also supposed to contribute to the pathogenesis of fibrosis. In addition, EMT can be induced by transforming growth factor &#946;, and EMT can be enhanced by pro-inflammatory cytokines like tumor necrosis factor &#945;. The gel contraction assay is an ideal in vitro model for the evaluation of contractility, which is one of the characteristic functions of fibroblasts and contributes to wound repair and fibrosis. Here, the development of a gel contraction assay is demonstrated for evaluating contractile ability of mesenchymal cells that underwent EMT.

Development of an In Vitro Assay to Evaluate Contractile Function of Mesenchymal Cells that Underwent Epithelial-Mesenchymal Transition

Here, we describe the development and application of a gel contraction assay for evaluating contractile function in mesenchymal cells that underwent epithelial-mesenchymal transition.

Fibrosis is often involved in the pathogenesis of various chronic progressive diseases such as interstitial pulmonary disease. Pathological hallmark is ...

Using In Vivo and Tissue and Cell Explant Approaches to Study the Morphogenesis and Pathogenesis of the Embryonic and Perinatal Aorta

The aorta is the largest artery in the body. The aortic wall is composed of an inner layer of endothelial cells, a middle layer of alternating elastic lamellae and smooth muscle cells (SMCs), and an outer layer of fibroblasts and extracellular matrix. In contrast to the widespread study of pathological models (e.g., atherosclerosis) in the adult aorta, much less is known about the embryonic and perinatal aorta. Here, we focus on SMCs and provide protocols for the analysis of the morphogenesis and pathogenesis of embryonic and perinatal aortic SMCs in normal development and disease. Specifically, the four protocols included are: i) in vivo embryonic fate mapping and clonal analysis; ii) explant embryonic aorta culture; iii) SMC isolation from the perinatal aorta; and iv) subcutaneous osmotic mini-pump placement in pregnant (or non-pregnant) mice. Thus, these approaches facilitate the investigation of the origin(s), fate, and clonal architecture of SMCs in the aorta in vivo. They allow for modulating embryonic aorta morphogenesis in utero by continuous exposure to pharmacological agents. In addition, isolated aortic tissue explants or aortic SMCs can be used to gain insights into the role of specific gene targets during fundamental processes such as muscularization, proliferation, and migration. These hypothesis-generating experiments on isolated SMCs and the explanted aorta can then be assessed in the in vivo context through pharmacological and genetic approaches.

Using In Vivo and Tissue and Cell Explant Approaches to Study the Morphogenesis and Pathogenesis of the Embryonic and Perinatal Aorta

Protocols for studying the embryonic and perinatal murine aorta using in vivo clonal analysis and fate mapping, aortic explants, and isolated smooth muscle cells are detailed here. These diverse approaches facilitate the investigation of the morphogenesis of the embryonic and perinatal aorta in normal development and the pathogenesis in disease.

The aorta is the largest artery in the body. The aortic wall is composed of an inner layer of endothelial cells, a middle layer of alternating elastic ...

Live Imaging of Mouse Secondary Palate Fusion

The fusion of the secondary palatal shelves to form the intact secondary palate is a key process in mammalian development and its disruption can lead to cleft secondary palate, a common congenital anomaly in humans. Secondary palate fusion has been extensively studied leading to several proposed cellular mechanisms that may mediate this process. However, these studies have been mostly performed on fixed embryonic tissues at progressive timepoints during development or in fixed explant cultures analyzed at static timepoints. Static analysis is limited for the analysis of dynamic morphogenetic processes such a palate fusion and what types of dynamic cellular behaviors mediate palatal fusion is incompletely understood. Here we describe a protocol for live imaging of ex vivo secondary palate fusion in mouse embryos. To examine cellular behaviors of palate fusion, epithelial-specific Keratin14-cre was used to label palate epithelial cells in ROSA26-mTmGflox reporter embryos. To visualize filamentous actin, Lifeact-mRFPruby reporter mice were used. Live imaging of secondary palate fusion was performed by dissecting recently-adhered secondary palatal shelves of embryonic day (E) 14.5 stage embryos and culturing in agarose-containing media on a glass bottom dish to enable imaging with an inverted confocal microscope. Using this method, we have detected a variety of novel cellular behaviors during secondary palate fusion. An appreciation of how distinct cell behaviors are coordinated in space and time greatly contributes to our understanding of this dynamic morphogenetic process. This protocol can be applied to mutant mouse lines, or cultures treated with pharmacological inhibitors to further advance understanding of how secondary palate fusion is controlled.

Here, we present a protocol for live imaging of mouse secondary palate fusion using confocal microscopy. This protocol can be used in combination with a variety of fluorescent reporter mouse lines, and with pathway inhibitors for mechanistic insight. This protocol can be adapted for live imaging in other developmental systems.

The fusion of the secondary palatal shelves to form the intact secondary palate is a key process in mammalian development and its disruption can lead to ...

Corneal Tissue Engineering: An In Vitro Model of the Stromal-nerve Interactions of the Human Cornea

Tissue engineering has gained substantial recognition due to the high demand for human cornea replacements with an estimated 10 million people worldwide suffering from corneal vision loss1. To address the demand for viable human corneas, significant progress in three-dimensional (3D) tissue engineering has been made2,3,4. These cornea models range from simple monolayer systems to multilayered models, leading to 3D full-thickness corneal equivalents2.
However, the use of a 3D tissue-engineered cornea in the context of in vitro disease models studied to date lacks resemblance to the multilayered 3D corneal tissue structure, function, and the networking of different cell types (i.e., nerve, epithelium, stroma, and endothelium)2,3. In addition, the demand for in vitro cornea tissue models has increased in an attempt to reduce animal testing for pharmaceutical products. Thus, more sophisticated models are required to better match systems to human physiological requirements, and the development of a model that is more relevant to the patient population is absolutely necessary. Given that multiple cell types in the cornea are affected by diseases and dystrophies, such as Keratoconus, Diabetic Keratopathy, and Fuchs, this model includes a 3D co-culture model of primary human corneal fibroblasts (HCFs) from healthy donors and neurons from the SH-SY5Y cell line. This allows us for the first time to investigate the interactions between the two cell types within the human corneal tissue. We believe that this model could potentially dissect the underlying mechanisms associated with the stromal-nerve interactions of corneal diseases that exhibit nerve damages. This 3D model mirrors the basic anatomical and physiological nature of the corneal tissue in vivo and can be used in the future as a tool for investigating corneal defects as well as screening the efficacy of various agents before animal testing.

Corneal Tissue Engineering: An In Vitro Model of the Stromal-nerve Interactions of the Human Cornea

This protocol describes a novel three-dimensional in vitro model, where corneal stromal cells and differentiated neuronal cells are cultured together to assist in the examination and understanding of the interactions of the two cell types.

Tissue engineering has gained substantial recognition due to the high demand for human cornea replacements with an estimated 10 million people worldwide ...

Adult Zebrafish Injury Models to Study the Effects of Prednisolone in Regenerating Bone Tissue

Zebrafish are able to regenerate various organs, including appendages (fins) after amputation. This involves the regeneration of bone, which regrows within roughly two weeks after injury. Furthermore, zebrafish are able to heal bone rapidly after trepanation of the skull, and repair fractures that can be easily introduced into zebrafish bony fin rays. These injury assays represent feasible experimental paradigms to test the effect of administered drugs on rapidly forming bone. Here, we describe the use of these 3 injury models and their combined use with systemic glucocorticoid treatment, which exerts bone inhibitory and immunosuppressive effects. We provide a workflow on how to prepare for immunosuppressive treatment in adult zebrafish, illustrate how to perform fin amputation, trepanation of calvarial bones, and fin fractures, and describe how the use of glucocorticoids affects both bone forming osteoblasts and cells of the monocyte/macrophage lineage as part of innate immunity in bone tissue.

Here, we describe 3 adult zebrafish injury models and their combined use with immunosuppressive drug treatment. We provide guidance on imaging of regenerating tissues and on detecting bone mineralization therein.

Zebrafish are able to regenerate various organs, including appendages (fins) after amputation. This involves the regeneration of bone, which regrows ...

An In Vitro Model of a Parallel-Plate Perfusion System to Study Bacterial Adherence to Graft Tissues

Various valved conduits and stent-mounted valves are used for right ventricular outflow tract (RVOT) valve replacement in patients with congenital heart disease. When using prosthetic materials however, these grafts are susceptible to bacterial infections and various host responses.
Identification of bacterial and host factors that play a vital role in endovascular adherence of microorganisms is of importance to better understand the pathophysiology of the onset of infections such as infective endocarditis (IE) and to develop preventive strategies. Therefore, the development of competent models to investigate bacterial adhesion under physiological shear conditions is necessary. Here, we describe the use of a newly designed in vitro perfusion chamber based on parallel plates that allows the study of bacterial adherence to different components of graft tissues such as exposed extracellular matrix, endothelial cells and inert areas. This method combined with colony-forming unit (CFU) counting is adequate to evaluate the propensity of graft materials towards bacterial adhesion under flow. Further on, the flow chamber system might be used to investigate the role of blood components in bacterial adhesion under shear conditions. We demonstrated that the source of tissue, their surface morphology and bacterial species specificity are not the major determining factors in bacterial adherence to graft tissues by using our in-house designed in vitro perfusion model.

An In Vitro Model of a Parallel-Plate Perfusion System to Study Bacterial Adherence to Graft Tissues

We describe an in-house designed in vitro flow chamber model, which allows the investigation of bacterial adherence to graft tissues.

Various valved conduits and stent-mounted valves are used for right ventricular outflow tract (RVOT) valve replacement in patients with congenital heart ...

An In Vivo Method to Study Mouse Blood-Testis Barrier Integrity

Spermatogenesis is the development of spermatogonia into mature spermatozoa in the seminiferous tubules of the testis. This process is supported by Sertoli cell junctions at the blood-testis barrier (BTB), which is the tightest tissue barrier in the mammalian body and segregates the seminiferous epithelium into two compartments, a basal and an adluminal. The BTB creates a unique microenvironment for germ cells in meiosis I/II and for the development of postmeiotic spermatids into spermatozoa via spermiogenesis. Here, we describe a reliable assay to monitor BTB integrity of mouse testis in vivo. An intact BTB blocks the diffusion of FITC-conjugated inulin from the basal to the apical compartment of the seminiferous tubules. This technique is suitable for studying gene candidates, viruses, or environmental toxicants that may affect BTB function or integrity, with an easy procedure and a minimal requirement of surgical skills compared to alternative methods.

An In Vivo Method to Study Mouse Blood-Testis Barrier Integrity

Here, we present a protocol to assess the blood-testis barrier integrity by injecting inulin-FITC into testes. This is an efficient in vivo method to study blood-testis barrier integrity that can be compromised by genetic and environmental elements.

Spermatogenesis is the development of spermatogonia into mature spermatozoa in the seminiferous tubules of the testis. This process is supported by ...

Recapitulating Suckling-to-Weaning Transition In Vitro using Fetal Intestinal Organoids

At the end of the suckling period, many mammalian species undergo major changes in the intestinal epithelium that are associated with the capability to digest solid food. This process is termed suckling-to-weaning transition and results in the replacement of neonatal epithelium with adult epithelium which goes hand in hand with metabolic and morphological adjustments. These complex developmental changes are the result of a genetic program that is intrinsic to the intestinal epithelial cells but can, to some extent, be modulated by extrinsic factors. Prolonged culture of mouse primary intestinal epithelial cells from late fetal period, recapitulates suckling-to-weaning transition in vitro. Here, we describe a detailed protocol for mouse fetal intestinal organoid culture best suited to model this process in vitro. We describe several useful assays designed to monitor the change of intestinal functions associated with suckling-to-weaning transition over time. Additionally, we include an example of an extrinsic factor that is capable to affect suckling-to-weaning transition in vivo, as a representation of modulating the timing of suckling-to-weaning transition in vitro. This in vitro approach can be used to study molecular mechanisms of the suckling-to-weaning transition as well as modulators of this process. Importantly, with respect to animal ethics in research, replacing in vivo models by this in vitro model contributes to refinement of animal experiments and possibly to a reduction in the use of animals to study gut maturation processes.

This protocol describes how to mimic suckling-to-weaning transition in vitro using mouse late fetal intestinal organoids cultured for 30 days.

At the end of the suckling period, many mammalian species undergo major changes in the intestinal epithelium that are associated with the capability to ...